1 /*
2 * Copyright 2008, The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 #include <stdio.h>
18 #include <stdarg.h>
19 #include <stdlib.h>
20 #include <unistd.h>
21 #include <errno.h>
22 #include <string.h>
23
24 #include <time.h>
25 #include <sys/time.h>
26 #include <poll.h>
27
28 #include <sys/socket.h>
29 #include <sys/select.h>
30 #include <sys/types.h>
31 #include <netinet/in.h>
32
33 #include <cutils/properties.h>
34 #define LOG_TAG "DHCP"
35 #include <cutils/log.h>
36
37 #include <dirent.h>
38
39 #include <netutils/ifc.h>
40 #include "dhcpmsg.h"
41 #include "packet.h"
42
43 #define VERBOSE 2
44
45 static int verbose = 1;
46 static char errmsg[2048];
47
48 typedef unsigned long long msecs_t;
49 #if VERBOSE
50 void dump_dhcp_msg();
51 #endif
52
get_msecs(void)53 msecs_t get_msecs(void)
54 {
55 struct timespec ts;
56
57 if (clock_gettime(CLOCK_MONOTONIC, &ts)) {
58 return 0;
59 } else {
60 return (((msecs_t) ts.tv_sec) * ((msecs_t) 1000)) +
61 (((msecs_t) ts.tv_nsec) / ((msecs_t) 1000000));
62 }
63 }
64
printerr(char * fmt,...)65 void printerr(char *fmt, ...)
66 {
67 va_list ap;
68
69 va_start(ap, fmt);
70 vsnprintf(errmsg, sizeof(errmsg), fmt, ap);
71 va_end(ap);
72
73 ALOGD("%s", errmsg);
74 }
75
dhcp_lasterror()76 const char *dhcp_lasterror()
77 {
78 return errmsg;
79 }
80
fatal(const char * reason)81 int fatal(const char *reason)
82 {
83 printerr("%s: %s\n", reason, strerror(errno));
84 return -1;
85 // exit(1);
86 }
87
ipaddr(in_addr_t addr)88 const char *ipaddr(in_addr_t addr)
89 {
90 struct in_addr in_addr;
91
92 in_addr.s_addr = addr;
93 return inet_ntoa(in_addr);
94 }
95
96 extern int ipv4NetmaskToPrefixLength(in_addr_t mask);
97
98 typedef struct dhcp_info dhcp_info;
99
100 struct dhcp_info {
101 uint32_t type;
102
103 uint32_t ipaddr;
104 uint32_t gateway;
105 uint32_t prefixLength;
106
107 uint32_t dns1;
108 uint32_t dns2;
109
110 uint32_t serveraddr;
111 uint32_t lease;
112 };
113
114 dhcp_info last_good_info;
115
get_dhcp_info(uint32_t * ipaddr,uint32_t * gateway,uint32_t * prefixLength,uint32_t * dns1,uint32_t * dns2,uint32_t * server,uint32_t * lease)116 void get_dhcp_info(uint32_t *ipaddr, uint32_t *gateway, uint32_t *prefixLength,
117 uint32_t *dns1, uint32_t *dns2, uint32_t *server,
118 uint32_t *lease)
119 {
120 *ipaddr = last_good_info.ipaddr;
121 *gateway = last_good_info.gateway;
122 *prefixLength = last_good_info.prefixLength;
123 *dns1 = last_good_info.dns1;
124 *dns2 = last_good_info.dns2;
125 *server = last_good_info.serveraddr;
126 *lease = last_good_info.lease;
127 }
128
dhcp_configure(const char * ifname,dhcp_info * info)129 static int dhcp_configure(const char *ifname, dhcp_info *info)
130 {
131 last_good_info = *info;
132 return ifc_configure(ifname, info->ipaddr, info->prefixLength, info->gateway,
133 info->dns1, info->dns2);
134 }
135
dhcp_type_to_name(uint32_t type)136 static const char *dhcp_type_to_name(uint32_t type)
137 {
138 switch(type) {
139 case DHCPDISCOVER: return "discover";
140 case DHCPOFFER: return "offer";
141 case DHCPREQUEST: return "request";
142 case DHCPDECLINE: return "decline";
143 case DHCPACK: return "ack";
144 case DHCPNAK: return "nak";
145 case DHCPRELEASE: return "release";
146 case DHCPINFORM: return "inform";
147 default: return "???";
148 }
149 }
150
dump_dhcp_info(dhcp_info * info)151 void dump_dhcp_info(dhcp_info *info)
152 {
153 char addr[20], gway[20];
154 ALOGD("--- dhcp %s (%d) ---",
155 dhcp_type_to_name(info->type), info->type);
156 strcpy(addr, ipaddr(info->ipaddr));
157 strcpy(gway, ipaddr(info->gateway));
158 ALOGD("ip %s gw %s prefixLength %d", addr, gway, info->prefixLength);
159 if (info->dns1) ALOGD("dns1: %s", ipaddr(info->dns1));
160 if (info->dns2) ALOGD("dns2: %s", ipaddr(info->dns2));
161 ALOGD("server %s, lease %d seconds",
162 ipaddr(info->serveraddr), info->lease);
163 }
164
165
decode_dhcp_msg(dhcp_msg * msg,int len,dhcp_info * info)166 int decode_dhcp_msg(dhcp_msg *msg, int len, dhcp_info *info)
167 {
168 uint8_t *x;
169 unsigned int opt;
170 int optlen;
171
172 memset(info, 0, sizeof(dhcp_info));
173 if (len < (DHCP_MSG_FIXED_SIZE + 4)) return -1;
174
175 len -= (DHCP_MSG_FIXED_SIZE + 4);
176
177 if (msg->options[0] != OPT_COOKIE1) return -1;
178 if (msg->options[1] != OPT_COOKIE2) return -1;
179 if (msg->options[2] != OPT_COOKIE3) return -1;
180 if (msg->options[3] != OPT_COOKIE4) return -1;
181
182 x = msg->options + 4;
183
184 while (len > 2) {
185 opt = *x++;
186 if (opt == OPT_PAD) {
187 len--;
188 continue;
189 }
190 if (opt == OPT_END) {
191 break;
192 }
193 optlen = *x++;
194 len -= 2;
195 if (optlen > len) {
196 break;
197 }
198 switch(opt) {
199 case OPT_SUBNET_MASK:
200 if (optlen >= 4) {
201 in_addr_t mask;
202 memcpy(&mask, x, 4);
203 info->prefixLength = ipv4NetmaskToPrefixLength(mask);
204 }
205 break;
206 case OPT_GATEWAY:
207 if (optlen >= 4) memcpy(&info->gateway, x, 4);
208 break;
209 case OPT_DNS:
210 if (optlen >= 4) memcpy(&info->dns1, x + 0, 4);
211 if (optlen >= 8) memcpy(&info->dns2, x + 4, 4);
212 break;
213 case OPT_LEASE_TIME:
214 if (optlen >= 4) {
215 memcpy(&info->lease, x, 4);
216 info->lease = ntohl(info->lease);
217 }
218 break;
219 case OPT_SERVER_ID:
220 if (optlen >= 4) memcpy(&info->serveraddr, x, 4);
221 break;
222 case OPT_MESSAGE_TYPE:
223 info->type = *x;
224 break;
225 default:
226 break;
227 }
228 x += optlen;
229 len -= optlen;
230 }
231
232 info->ipaddr = msg->yiaddr;
233
234 return 0;
235 }
236
237 #if VERBOSE
238
hex2str(char * buf,size_t buf_size,const unsigned char * array,int len)239 static void hex2str(char *buf, size_t buf_size, const unsigned char *array, int len)
240 {
241 int i;
242 char *cp = buf;
243 char *buf_end = buf + buf_size;
244 for (i = 0; i < len; i++) {
245 cp += snprintf(cp, buf_end - cp, " %02x ", array[i]);
246 }
247 }
248
dump_dhcp_msg(dhcp_msg * msg,int len)249 void dump_dhcp_msg(dhcp_msg *msg, int len)
250 {
251 unsigned char *x;
252 unsigned int n,c;
253 int optsz;
254 const char *name;
255 char buf[2048];
256
257 ALOGD("===== DHCP message:");
258 if (len < DHCP_MSG_FIXED_SIZE) {
259 ALOGD("Invalid length %d, should be %d", len, DHCP_MSG_FIXED_SIZE);
260 return;
261 }
262
263 len -= DHCP_MSG_FIXED_SIZE;
264
265 if (msg->op == OP_BOOTREQUEST)
266 name = "BOOTREQUEST";
267 else if (msg->op == OP_BOOTREPLY)
268 name = "BOOTREPLY";
269 else
270 name = "????";
271 ALOGD("op = %s (%d), htype = %d, hlen = %d, hops = %d",
272 name, msg->op, msg->htype, msg->hlen, msg->hops);
273 ALOGD("xid = 0x%08x secs = %d, flags = 0x%04x optlen = %d",
274 ntohl(msg->xid), ntohs(msg->secs), ntohs(msg->flags), len);
275 ALOGD("ciaddr = %s", ipaddr(msg->ciaddr));
276 ALOGD("yiaddr = %s", ipaddr(msg->yiaddr));
277 ALOGD("siaddr = %s", ipaddr(msg->siaddr));
278 ALOGD("giaddr = %s", ipaddr(msg->giaddr));
279
280 c = msg->hlen > 16 ? 16 : msg->hlen;
281 hex2str(buf, sizeof(buf), msg->chaddr, c);
282 ALOGD("chaddr = {%s}", buf);
283
284 for (n = 0; n < 64; n++) {
285 unsigned char x = msg->sname[n];
286 if ((x < ' ') || (x > 127)) {
287 if (x == 0) break;
288 msg->sname[n] = '.';
289 }
290 }
291 msg->sname[63] = 0;
292
293 for (n = 0; n < 128; n++) {
294 unsigned char x = msg->file[n];
295 if ((x < ' ') || (x > 127)) {
296 if (x == 0) break;
297 msg->file[n] = '.';
298 }
299 }
300 msg->file[127] = 0;
301
302 ALOGD("sname = '%s'", msg->sname);
303 ALOGD("file = '%s'", msg->file);
304
305 if (len < 4) return;
306 len -= 4;
307 x = msg->options + 4;
308
309 while (len > 2) {
310 if (*x == 0) {
311 x++;
312 len--;
313 continue;
314 }
315 if (*x == OPT_END) {
316 break;
317 }
318 len -= 2;
319 optsz = x[1];
320 if (optsz > len) break;
321 if (x[0] == OPT_DOMAIN_NAME || x[0] == OPT_MESSAGE) {
322 if ((unsigned int)optsz < sizeof(buf) - 1) {
323 n = optsz;
324 } else {
325 n = sizeof(buf) - 1;
326 }
327 memcpy(buf, &x[2], n);
328 buf[n] = '\0';
329 } else {
330 hex2str(buf, sizeof(buf), &x[2], optsz);
331 }
332 if (x[0] == OPT_MESSAGE_TYPE)
333 name = dhcp_type_to_name(x[2]);
334 else
335 name = NULL;
336 ALOGD("op %d len %d {%s} %s", x[0], optsz, buf, name == NULL ? "" : name);
337 len -= optsz;
338 x = x + optsz + 2;
339 }
340 }
341
342 #endif
343
send_message(int sock,int if_index,dhcp_msg * msg,int size)344 static int send_message(int sock, int if_index, dhcp_msg *msg, int size)
345 {
346 #if VERBOSE > 1
347 dump_dhcp_msg(msg, size);
348 #endif
349 return send_packet(sock, if_index, msg, size, INADDR_ANY, INADDR_BROADCAST,
350 PORT_BOOTP_CLIENT, PORT_BOOTP_SERVER);
351 }
352
is_valid_reply(dhcp_msg * msg,dhcp_msg * reply,int sz)353 static int is_valid_reply(dhcp_msg *msg, dhcp_msg *reply, int sz)
354 {
355 if (sz < DHCP_MSG_FIXED_SIZE) {
356 if (verbose) ALOGD("Wrong size %d != %d\n", sz, DHCP_MSG_FIXED_SIZE);
357 return 0;
358 }
359 if (reply->op != OP_BOOTREPLY) {
360 if (verbose) ALOGD("Wrong Op %d != %d\n", reply->op, OP_BOOTREPLY);
361 return 0;
362 }
363 if (reply->xid != msg->xid) {
364 if (verbose) ALOGD("Wrong Xid 0x%x != 0x%x\n", ntohl(reply->xid),
365 ntohl(msg->xid));
366 return 0;
367 }
368 if (reply->htype != msg->htype) {
369 if (verbose) ALOGD("Wrong Htype %d != %d\n", reply->htype, msg->htype);
370 return 0;
371 }
372 if (reply->hlen != msg->hlen) {
373 if (verbose) ALOGD("Wrong Hlen %d != %d\n", reply->hlen, msg->hlen);
374 return 0;
375 }
376 if (memcmp(msg->chaddr, reply->chaddr, msg->hlen)) {
377 if (verbose) ALOGD("Wrong chaddr %x != %x\n", *(reply->chaddr),*(msg->chaddr));
378 return 0;
379 }
380 return 1;
381 }
382
383 #define STATE_SELECTING 1
384 #define STATE_REQUESTING 2
385
386 #define TIMEOUT_INITIAL 4000
387 #define TIMEOUT_MAX 32000
388
dhcp_init_ifc(const char * ifname)389 int dhcp_init_ifc(const char *ifname)
390 {
391 dhcp_msg discover_msg;
392 dhcp_msg request_msg;
393 dhcp_msg reply;
394 dhcp_msg *msg;
395 dhcp_info info;
396 int s, r, size;
397 int valid_reply;
398 uint32_t xid;
399 unsigned char hwaddr[6];
400 struct pollfd pfd;
401 unsigned int state;
402 unsigned int timeout;
403 int if_index;
404
405 xid = (uint32_t) get_msecs();
406
407 if (ifc_get_hwaddr(ifname, hwaddr)) {
408 return fatal("cannot obtain interface address");
409 }
410 if (ifc_get_ifindex(ifname, &if_index)) {
411 return fatal("cannot obtain interface index");
412 }
413
414 s = open_raw_socket(ifname, hwaddr, if_index);
415
416 timeout = TIMEOUT_INITIAL;
417 state = STATE_SELECTING;
418 info.type = 0;
419 goto transmit;
420
421 for (;;) {
422 pfd.fd = s;
423 pfd.events = POLLIN;
424 pfd.revents = 0;
425 r = poll(&pfd, 1, timeout);
426
427 if (r == 0) {
428 #if VERBOSE
429 printerr("TIMEOUT\n");
430 #endif
431 if (timeout >= TIMEOUT_MAX) {
432 printerr("timed out\n");
433 if ( info.type == DHCPOFFER ) {
434 printerr("no acknowledgement from DHCP server\nconfiguring %s with offered parameters\n", ifname);
435 return dhcp_configure(ifname, &info);
436 }
437 errno = ETIME;
438 close(s);
439 return -1;
440 }
441 timeout = timeout * 2;
442
443 transmit:
444 size = 0;
445 msg = NULL;
446 switch(state) {
447 case STATE_SELECTING:
448 msg = &discover_msg;
449 size = init_dhcp_discover_msg(msg, hwaddr, xid);
450 break;
451 case STATE_REQUESTING:
452 msg = &request_msg;
453 size = init_dhcp_request_msg(msg, hwaddr, xid, info.ipaddr, info.serveraddr);
454 break;
455 default:
456 r = 0;
457 }
458 if (size != 0) {
459 r = send_message(s, if_index, msg, size);
460 if (r < 0) {
461 printerr("error sending dhcp msg: %s\n", strerror(errno));
462 }
463 }
464 continue;
465 }
466
467 if (r < 0) {
468 if ((errno == EAGAIN) || (errno == EINTR)) {
469 continue;
470 }
471 return fatal("poll failed");
472 }
473
474 errno = 0;
475 r = receive_packet(s, &reply);
476 if (r < 0) {
477 if (errno != 0) {
478 ALOGD("receive_packet failed (%d): %s", r, strerror(errno));
479 if (errno == ENETDOWN || errno == ENXIO) {
480 return -1;
481 }
482 }
483 continue;
484 }
485
486 #if VERBOSE > 1
487 dump_dhcp_msg(&reply, r);
488 #endif
489 decode_dhcp_msg(&reply, r, &info);
490
491 if (state == STATE_SELECTING) {
492 valid_reply = is_valid_reply(&discover_msg, &reply, r);
493 } else {
494 valid_reply = is_valid_reply(&request_msg, &reply, r);
495 }
496 if (!valid_reply) {
497 printerr("invalid reply\n");
498 continue;
499 }
500
501 if (verbose) dump_dhcp_info(&info);
502
503 switch(state) {
504 case STATE_SELECTING:
505 if (info.type == DHCPOFFER) {
506 state = STATE_REQUESTING;
507 timeout = TIMEOUT_INITIAL;
508 xid++;
509 goto transmit;
510 }
511 break;
512 case STATE_REQUESTING:
513 if (info.type == DHCPACK) {
514 printerr("configuring %s\n", ifname);
515 close(s);
516 return dhcp_configure(ifname, &info);
517 } else if (info.type == DHCPNAK) {
518 printerr("configuration request denied\n");
519 close(s);
520 return -1;
521 } else {
522 printerr("ignoring %s message in state %d\n",
523 dhcp_type_to_name(info.type), state);
524 }
525 break;
526 }
527 }
528 close(s);
529 return 0;
530 }
531
do_dhcp(char * iname)532 int do_dhcp(char *iname)
533 {
534 if (ifc_set_addr(iname, 0)) {
535 printerr("failed to set ip addr for %s to 0.0.0.0: %s\n", iname, strerror(errno));
536 return -1;
537 }
538
539 if (ifc_up(iname)) {
540 printerr("failed to bring up interface %s: %s\n", iname, strerror(errno));
541 return -1;
542 }
543
544 return dhcp_init_ifc(iname);
545 }
546